Abstract
Despite their conceptual similarities and importance for effective health management, the relationship between health literacy and eHealth literacy remains poorly understood. This systematic review investigated the statistical association between health literacy and eHealth literacy in adults, along with study-level moderators and biopsychosocial correlates. CINAHL, Embase, Emcare, PubMed, ProQuest, PsycINFO, and Web of Science were searched until January 2025. Methodological reporting quality (QualSyst Checklist) was assessed and between-study heterogeneity explored using random and mixed-effects modeling. Twenty-three observational studies (N = 25 505 participants), all characterized by high methodological quality, were included. A weak positive relationship between overall health literacy and eHealth literacy was identified [r = 0.29, CI (0.21, 0.37)], with Category 2/comprehensive measures of health literacy correlating more strongly with eHealth literacy than Category 1/functional measures. Individual-level factors, including higher educational attainment, economic advantage, positive health behaviors, strong self-efficacy, and the ability to use digital resources were consistently linked to higher health literacy and eHealth literacy. The findings suggest that health literacy and eHealth literacy should continue to be researched in tandem to understand their impact on health outcomes in the digital age. Further research is also needed to understand how the surrounding environment, together with individual factors such as age and cultural background, influences the development of health literacy and eHealth literacy. Such studies are crucial for addressing disparities and enhancing access to health information and services.